Mark,
Interesting question; I haven't read the organizations thread so I don't know the discussion there.

A couple of quick google searches came up the number 192 for the number of countries in the world. I don't know if I would hazard a guess that Aikido is practiced in all of them, but certainly in most of them I would think.

With that number of countries in mind I would then venture to speculate that the number of Aikidoka worldwide would certainly be in the hundreds of thousands, if not millions.

Harmony does not mean that there are no conflicts,
for the dynamic spiral of existence embraces both extremes.